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I really prefer the hoods up method now, but I feel it does create a synthetic atmosphere which handicaps stock vs bottom breathers. Enough said on this.

My evaluation of the 2002 C5.

1) The reason for the inconsistancy of the stock numbers jumping from 350 to 335 in less than two minutes is, I believe, due in part, to the tighter piston to wall clearances. GM had nothing but grief with the oil consumption issue which seemed to affect just a few customers. They responded responsibly by offering those folks a fix which would solve any excessive oil burning issues. In the new Z06, these issues are gone forever, but a new crop of issues have grown out of this tighter motor.

What I feel has happened is that the tighter bores, even with coated pistons, are going to have to be given several thousand additiional miles to loosen up. Imagine what happens on dynos in GA during 107 degree days, to a dyno pull on a new 02 motor. The benefit to the consumer is longer engine life.

There isn't a hint of piston knock.

The 20 RWHP promised is there. A 350 pull only needs to compare to about 338 to be 20 more at the flywheel.

GM inadvertantly left even more HP under the table than on the 2001 Z06. Our TRIC pulled an average of 12 to 14 RWHP out of the 2001, with the SideWinder showing over 16. The 16 was at 198 degrees. Just think what we will see at 180.

It's easy for these forums to make assumptions or jump to conclusions without sufficient test information, which can ultimately lead to a lack of new car sales due to misconceptions.

The 2002 Corvette Z06 is the finest, most highly tuned performance vehicle in its class and beyond. You will not believe just how fast this thing is until you mod it.

Taking the screen out was not worth the bother. The laminar screen helped the 01 develop cleaner a/f ratio feedback, which may be responsible for some of the leanest.

Clean burn? I'll say. The plugs are pure white!.

Oil consumption: Only 1/2 Qt. in 3300 miles (just changed to Torco Racing Synthetic) with 20 dyno pulls.

We have now achieved over 430 HP, so far, and the dyno numbers, ARE consistant. This was without any cooling tricks, and without a bottom breather. (No the TRIC is not being phased out, just put in its place)

We found that the heat soak was so intense with the hood down method as to distort the dyno numbers to where they did not make sense. Three of the stock spark plugs had melting tips, which obviously caused extreme pre-ignition.

As we continue to discover just how strong this motor really is, I think with simple cooling mods, and changes in the spark plugs (We used the Champion RS12YC copper plugs for our T-1) and thermostat, fan settings, owners will find another 5 or 6 RWHP (355 range) and more importantly, will not lose HP under normal driving conditions. All of these mods will be available at very low cost.

Best

Jim Hall
Halltech Systems, Inc.
 

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Yesterday, I had an interesting conversation with the owner of Woodbridge DynoTech, the shop I will be dyno testing at on 9/22. This gentleman has had a great deal of experience with this type of testing (using DynoJet equipment) on Corvettes and other performance vehicles. He does a large volume of testing and tuning for cars used in competition. One of the things we discussed was the hood open, hood down issue. He told me that he always tests with the hood open - and he does this for two basic reasons:

1). The developer of his test equipment recommends it; and

2). It just makes good sense. Why good sense? Because testing a stationary vehicle at high RPMs within a building (his unit is not portable) will promote excessive underhood heat, which is not representative of "real world" conditions. In the real world, your vehicle is moving and ingesting air into the engine compartment. And although a fan is traditionally positioned in front of the tested vehicle, by itself, it cannot make up the difference.

Now this process does create somewhat of a synthetic atmosphere, but it seems to be the best compromise available.

The following is my humble, unwashed opinion only. I think just about any of the aftermarket air intake units be they opened up, higher quality filter underhood units such as the Blackwing, or cooler air intakes such as those made by Halltech or Vortex or whoever, will make some additional power. Afterall, it only stands to reason that if we view the engine as essentially an air pump, the more (and cooler) air we get in, and the more we get out, the more power made. Turbocharging, supercharging, head work, cams, headers are all ways to maximize the air pump.

All of the cool air systems I have seen are essentially tubes of some sort carrying ending in some type of high quality filter, sometimes placed within some type box or pick-up, which is positioned to pick-up cooler air. It is exactly the same approach used by the manufacturers such as AEM, who provide these to the Honda - Mitsu crowd.

They all make power, and I continue to believe IMHO, that the differences between the better units, are statistically minimal.

One other comment. These engines do run too hot, just like my C4s did, so a change to a 172 thermo, and fan controller kit certainly will reduce a little power loss.

I am very happy with my '02 to-date, and I think Jim is on the right track re additional break-in possibly being required due to the tighter bores. Since my car only has a little over 1,000 miles on it, it will be interesting to see if more power is made as the miles accumulate.

Given that, I do not understand why the "stock numbers jumping from 350 to 335 in less than two minutes is due to the tighter piston to wall clearances" If it takes considerably longer for break-in, that does not explain such variances within two minutes. Perhaps heat soak??
 
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Heat soak

I am on my way into the shop. I'll post the pulls so that they can be disected.

At R&D Dyno, they have two fans which literally force air out at 35 MPH (old home heating units). While they don't duplicate the real world entirely, by running them in the front of the car, and starting the pulls at the lowest temp the thermo can allow, reproduces real world better than any other condition.

The Dyno testing done at Powertrain Dynamics basically told me that fans and hood up or down, doesn't matter at all. He also told me that the dyno numbers would increase with each consecutive pull. They did not, and he is wrong about the fans.

When R&D lifts the hood (told by DynoJet to do it this way) coupled with the fans blowing in the front, what you get is the Army. "Be, all that you can be"

My opinion still: Sythetic conditions, but on the 2002, you must run everything as cool as possible to see accurate numbers from which to gauge further mods.

The dyno should be used to evaluate one mod vs stock or another mod. Peak numbers never really show whats happening in the real world at partial throttle or the delivery of power, which to me is the torque numbers. Those numbers are never discussed and are much more important than peak HP numbers.

Jim
 

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Halltech said:
I don't have all the answers, and I'm wrong about as much as anyone else...

1) The reason for the inconsistancy of the stock numbers jumping from 350 to 335 in less than two minutes is due to the tighter piston to wall clearances. GM had nothing but grief with the oil consumption issue which seemed to affect just a few customers. They responded responsibly by offering those folks a fix which would solve any excessive oil burning issues. In the new Z06, these issues are gone forever, but a new crop of issues have grown out of this tighter motor.
[/B]
"I don't have all the answers, and I'm wrong about as much as anyone else..." Me too! Hey, were all fallible ;) - except maybe that other vendor ;)

Here are my 2 cents, Jim, maybe you can clarify your position:

I am not sure that I understand your reasoning here and I would agree with BLEUBYU, based on the information that your providing (so far), I'm not sure why you think the tighter clearances are the reason for the power loss on the second pull. What aren't you telling us?

With less than two minutes between the pulls, you most certainly hadn't cooled the engine back down to the same temperature as the first pull. So yes, "in theory", the pistons could be expanding somewhat in size and tightening in the bore.

But before this actually happens "in reality", with a measurable power loss, I would think that you need a much longer duration wide open throttle run and abnormally high engine temperatures to reach a typical "hot-scuff" condition. Any GM engineers out there????

I can't believe the clearances are now so tight that we're loosing power at your temps because of increased piston/cylinder wall friction. With WOT pulls at 240+ degrees of coolant temp, I think I might start to buy into your reasoning. But if thats happening at normal engine operating temps, it isn't going to be good for the longevity of these '02 engines no matter what they've coated the pistons with.

Instead, my first guess for the power loss would be the typical heat related power thiefs. For those two dyno pulls, what were the deltas of the coolant temps, intake air temps and timing? Do these deltas alone to account for the power difference?

All rebuttals welcomed!
:cheers:
 

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Halltech said:
I don't have all the answers, and I'm wrong about as much as anyone else. What I do have is 41 years of drag race engine building, most of it in the motorcycle arena, but I engineered a completely new engine based on the Honda 24 valve 6 cylinder engine.

I started with a billet piece of aluminum and created, with the help of our machinist, a 1550 cc turbocharged engine with a billet aluminum block, that everyone in the motorcycle industry laughed at. Couldn't be done. Why? The stock block could not be sleeved and bored any larger than 69mm. We got 76mm with a new block and custom sleeves, then stroked the crankshaft, added Carillo rods and $25,000 worth of other one off parts.

The result was a bike that on its first trip to the drags ran 9.50 @ 150 MPH, with the slick smoking the entire 1/4 mile.
Hummm ... I've got buddy with a Hayabusa that only has intake, exhaust and drop in cams that does 9.28 at 153 MPH quater mile. And thats on a street tire and shifting manually. Its also ridden on the street everyday. Total cost only $13K -- and that INCLUDES the bike :D:D.


Now about the Z. White plugs :eek: -- sounds alittle lean to me. BTW, have you ever sniffed the exhaust to see where these cars A/F under WOT is at? Anyway -- thanks for the info about the Zs.
 

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As far as the power loss with consecutive pulls on the 2002 with tighter cylinder clearance. Each time the car is ran WOT on the dyno, the pistons are getting heated up. As they heatup, they expand alittle bit. They are aluminum, and they transfere heat well, and also expand well. So as you can now imagine, with back to back pulls, the piston clearance starts getting tighter and tighter -- mostly with an engine with only say 500 miles on it. This starts robbing HP due to added internal engine friction. This is why GM put the polymer coating on the pistons, so they wouldn't scuff if they got too tight due to extended WOT conditions.
 

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I think he means white as in the insulator being white and clean....which indicates that combustion is near perfect......

JC
 

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ZeeOhSix said:
As far as the power loss with consecutive pulls on the 2002 with tighter cylinder clearance. Each time the car is ran WOT on the dyno, the pistons are getting heated up. As they heatup, they expand alittle bit. They are aluminum, and they transfere heat well, and also expand well. So as you can now imagine, with back to back pulls, the piston clearance starts getting tighter and tighter -- mostly with an engine with only say 500 miles on it. This starts robbing HP due to added internal engine friction. This is why GM put the polymer coating on the pistons, so they wouldn't scuff if they got too tight due to extended WOT conditions.
Yup, I agree with everything you said in basis; I'm thinking the same thoughts. But Jim said this was happening on the very next pull, not after several consecutive pulls on a long day of testing.

I'm theorizing that a 25 horsepower loss due to increased piston/bore friction after one short duration WOT dyno pull doesn't make sense. I would think that the engine temps would need to be much higher - holding WOT for much longer durations, i.e. road racing conditions.

You could see the same losses with the computer pulling timing and the reduced air density of the hot intake air (kind of like my theorizing on this subject, a lot of not *so* dense hot air :lol: ). If Jim will show us his Autotap numbers, then maybe he could prove his theory right.

The cylinder wall sleeves are cast iron and the pistons aluminum (probably an aluminum-silicon alloy), dissimilar metals with different rates of expansion. The pistons have more surface area exposed to the flame initially. So maybe it is possible that the cylinder expansion lags far enough behind the pistons that we are seeing this much friction at these *relatively* low engine operating temps. I just didn't expect to see that much added friction until the engine got much hotter.
 
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Re: Re: Jim Hall's Evaluation of the Z06 2002

pmontelo said:


"I don't have all the answers, and I'm wrong about as much as anyone else..." Me too! Hey, were all fallible ;) - except maybe that other vendor ;)

Here are my 2 cents, Jim, maybe you can clarify your position:



But before this actually happens "in reality", with a measurable power loss, I would think that you need a much longer duration wide open throttle run and abnormally high engine temperatures to reach a typical "hot-scuff" condition. Any GM engineers out there????

I can't believe the clearances are now so tight that we're loosing power at your temps because of increased piston/cylinder wall friction. With WOT pulls at 240+ degrees of coolant temp, I think I might start to buy into your reasoning. But if thats happening at normal engine operating temps, it isn't going to be good for the longevity of these '02 engines no matter what they've coated the pistons with.

Instead, my first guess for the power loss would be the typical heat related power thiefs. For those two dyno pulls, what were the deltas of the coolant temps, intake air temps and timing? Do these deltas alone to account for the power difference?

Very simply: Tighter bores+ more tension on the ring package equals more friction. More friction equals more heat; more heat in this area equals a loss of power. As the motor loosens up, I predict another 10 RWHP easy.

All rebuttals welcomed!
:cheers:
Very simply: Tighter bores+ more tention on the ring package equals more friction. More friction equals more heat; more heat in this area equals a loss of power. As the motor loosens up, I predict another 10 RWHP easy.


Jim Hall
 

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I think we have somewhat of a concensus. For "consistency":

hood up
fans blowing in front
allow for cooldown

Furthermore, to optimize for "best case" dyno #s:

Good idea to install lower temp stat and a radiator cooling fans override switch. BTW, does turning on the electronic A/C force the radiator cooling fans to run like it did in the C4?

Another factor that might enter into this is the octane rating in the tank. If 93 or 94 (but not any higher or hp may drop), the ESC system will be less susceptible to heat buildup and retard the spark. But allowing for sufficient cooldown between pulls may still be the best safeguard in this regard. Conversely, try to do your dyno test in the dead of winter and take the hit via the SAE CF which may still bias the results to higher measurements even after "correction".

If the dynojet rollers require the car under test to be on a lift, some dyno operator like to put their own cooling fan "under the car directed at the catalytic convert to prevent it from overheating.

In all dyno sessions the one variable that is hardest to control I think is allowing for sufficient cooldown time between pulls. Unless you have the dyno shop all to yourself, usually it is not practical in the interest of time.

The one other thing that I think has some subtle effect on the results is how accurately the rear wheels are precisely placed perpendicular to the dyno roller axis. In a "rush" the dyno operator allows that to get a bit off center. Might that not cause some small amount of additional loss in the RWHP measurement?
 

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Dsinned,
"one other thing that I think has some subtle effect on the results is how accurately the rear wheels are precisely placed perpendicular to the dyno roller axis. In a "rush" the dyno operator allows that to get a bit off center. Might that not cause some small amount of additional loss in the RWHP measurement?"

I've wondered the same thing and I think that you're on to something. Most dyno shops strap the car down so tight that there's no opportunity for the car to center itself. You'd think that if it's cocked by as little as 1 degree from center that you'd loose significant power.
 

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Dsinned,
"one other thing that I think has some subtle effect on the results is how accurately the rear wheels are precisely placed perpendicular to the dyno roller axis. In a "rush" the dyno operator allows that to get a bit off center. Might that not cause some small amount of additional loss in the RWHP measurement?"

I've wondered the same thing and I think that you're on to something. Most dyno shops strap the car down so tight that there's no opportunity for the car to center itself. You'd think that if it's cocked by as little as 1 degree from center that you'd lose significant power.
 

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Anybody mention tire pressures???
 
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Tire pressure

I was told by two operators that letting air out of the rears can cause 15 or so lost HP.

JIm
 

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My car was not centered on the dyno when I ran a 337/325. I also asked the dyno operator if the car having low pressure in the tires made any difference and he (A young kid full of BS about eveything else.) said it would not make any difference. I guess now I know the truth.......................................................

I am going to buy an AutoTap. Any suggestions on where to get it?

Carl
 
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AutoTap

www.AutoTap.com

Very inexpensive, but you need a laptop with a serial port connector.

The new Windows software actually lets you see the air/fuel ratio now, not just the O2 voltage.

The new software is spectacular. Everyone should have one.

Our TRIC T-1 less the cooling changes scheduled for Monday, was AutoTapped and the a/f ratios for all closed loop fuel cells are at 14.7 to 1 but more importantly the Long Term Trims have settled in close to zero (meaning very little correction needed). This all since the injectors were installed.

Monday we have an appointment with RC Engineerings Russ Collins of Top Fuel Motorcycle fame and misfortune, to diagnose the stock 2002 injectors. I suspect they may have been reduced a little, but that's just an opionion at this point. We test and monitor all 8, then compare with my injectors, which are WORKING!

Jim
 
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